This invention relates to shaving devices and concerns a safety razor blade unit having at least one blade with a cutting edge which is moved across the surface of the skin being shaved by means of a handle to which the blade unit is attached. The blade unit may be mounted detachably on the handle to enable the blade unit to be replaced by a fresh blade unit when the blade sharpness has diminished to an unsatisfactory level, or it may be attached permanently to the handle with the intention that the entire razor be discarded when the blade or blades have become dulled. Razor blade units generally include a guard which defines a surface for contacting the skin in front of the blade(s) and a cap for contacting the skin behind the blade(s), the cap and guard serving important roles in establishing the so-called xe2x80x9cshaving geometryxe2x80x9d, i.e. the parameters which determine the blade orientation and position relative to the skin during shaving. The present invention is especially concerned with the guard and/or cap of a razor blade unit.
It is known to provide a skin engaging guard or cap with surface configurations intended to produce pleasant tactile sensations during shaving, for example as described in U.S. Pat. No. 5,191,712.
The present invention aims to provide an improved surface structure on a cap or guard and in accordance with this object the invention resides in a safety razor blade unit having at least one elongate blade, and a skin engaging member defining a surface for contact with the skin during shaving, said surface being defined by spaced hollow projections extending upwardly from a base and open at their upper ends, the projections being formed of a resiliently flexible material whereby the upper ends of the projections can deflect locally under forces encountered during shaving.
Conveniently the projections can take the form of tubes which may be arranged in one or more rows extending along the base generally parallel to the razor blade edge(s), with at least 10 tubes per row. Suitably the projections have a height in the range of 0.38 mm to 1.5 mm preferably about 0.75 mm, an outer diameter from 0.40 mm to 3.00 mm, preferably about 0.60 mm, and with the wall thickness at the base to height ratio being between 1:1 and 1:15, preferably around 1:7.5. An appropriate spacing between adjacent projections, at least in the direction parallel to the blade edge(s), is in the range from 0.10 mm to a distance equal to the maximum dimension of the projection measured in said direction, the spacing in a currently preferred embodiment being 0.20 mm. If desired adjacent projections can be interconnected, such as by membranes moulded integrally with the projections.
The projections may be of constant internal and external diameter, but they can also taper in either direction along their length both inside and/or outside. A suitable wall thickness for the hollow projections has been found to be around 0.10 mm, at least at their upper edges. It is not essential for the projections to be completely annular in cross-section and they can have one or more longitudinal slots extending over their full height or only part of their height.
In the preferred embodiments described in more detail below, tubes of circular in cross-section are provided but this is not essential and other cross-sectional shapes are possible, such as elliptical, square or D-shaped.
The upper end faces of the projections can be substantially flat and coplanar. Alternatively the upper end faces may be inclined forwardly and downwardly toward the base. Also the upper edges of the projections may be rounded off, at least at the fronts of the projections.
With a razor blade unit according to the invention the projections forming the skin contacting surface of the skin engaging member, because they are hollow and open at the top, can be more responsive to local forces during shaving, e.g. due to a hair being encountered, than solid projections and as a consequence there may be less tendency for hairs to be deflected laterally by the projections. Furthermore, the hollow projections form pockets in which moisture or a shaving preparation, such as shaving soap or the like, applied to the skin to facilitate the shaving operation, can collect in small amounts. A shaving preparation generally serves to lubricate the skin. Any preparation collected in the pockets may assist in lubricating the skin, e.g. at the end of a shave when most of the preparation applied will have been removed, or perhaps at the beginning of a shave if the skin has not been well prepared. The skin engaging member could even be supplied with the pockets containing shaving enhancement product, or possibly communicating with a reservoir of such a product to be dispensed through the pockets, in essentially the same manner as described in relation to the pocketed skin engaging members disclosed in our International Patent Application No. PCT/US95/08634 (WO96/02369). With the present invention delivery of product from the pockets may be enhanced by a pumping action due to the projections flexing as the skin contacting member moves across the surface of the skin.